Candidate's broad objectives: The candidate is a board certified internist and geriatrician with special interest in sleep disorders. He plans to become an independent researcher and expert in the management of sleep disorders of older adults. During the last three years, he has been involved in research activities that examined the relationship between sleep-disordered breathing (SDB) and nocturia, two common health problems of older adults. The candidate is applying for the Mentored-Patient Oriented Research Career Development Award to investigate the mechanism mediating the relationship between these two conditions. The planned research is based on the following hypotheses. SDB leads to increase in sympathetic activity and non-dipping of nocturnal blood pressure. To offset the effects of increased sympathetic activity, secretion of atrial natriuretic peptide (AMP) is increased. In addition to vasodilation, the increase in ANP results in nocturnal polyuria and nocturia. Research Plan: 130 community dwelling older adults will be admitted to the General Clinical Research Center for 48 hours. During their stay in GCRC, measurement of continuous 24-hour blood pressure, collection of 24-hour urine and serial blood samples, and sleep study will be performed. Plasma norepinephrine and ANP levels and urine ANP levels will be measured. Possible causal pathways linking SDB with increased norepinephrine levels, non-dipping of nocturnal blood pressure, increased ANP levels and nocturnal polyuria will be assessed using the path analysis statistical method. Comparison of effects of SDB will be made between African American and Caucasian racial groups. Significance of the Project: The result of the study will underscore the clinical significance of SDB among older adults. It will also provide useful information to clinicians and facilitate the diagnosis and management of SDB and nocturia among older adults. Environment: The candidate has the support of the Division of Geriatrics and Gerontology, the Sleep Disorders Center, and the General Clinical Research Center of Emory University School of Medicine that will help him to realize his goals and objectives.